Four-year-old Epix has signed a carriage agreement with Time Warner Cable, making it available in 44 million homes — with more deals in the works, The Post has learned.

As it grows from being just a niche channel to being available in roughly 40 percent of US homes, it is more and more a rival to HBO, Showtime and Starz.

The service on TWC kicks off March 18.

Epix offers subscribers a host of fresh movies and specials, usually 10 months after their box office release.

To entice customers to subscribe to Epix, TWC will offer a free trial period, after which consumers can sign on for $4.99 per month.

Epix is owned by three studios — Viacom’s Paramount, MGM and Lionsgate — and though it has struggled to sign up cable and satellite operators to distribute its movies, it has aggressively sought digital partners, including Netflix, Microsoft’s Xbox Connect and Sony’s Playstation 4.

Mark Greenberg, president and CEO of Epix, is expected to sign other new deals in the coming months, sources said.

Epix does not yet have agreements with AT&T’s U-Verse, Comcast and DirecTV, among others.

A deal with Cablevision is unlikely to be made until the cable operator and Viacom are able to figure out a long-standing lawsuit over channel bundling.

Epix has distribution agreements with Cox, Charter and Dish.

Despite its growth, Epix is still a minnow next to the competition: HBO counts 29.2 million subscribers, Showtime 22.8 million and Starz 22 million, compared with 5.7 million for Epix as of last September, according to SNL Kagan.

But Epix’ subscribers are actually closer to 10 million, according to sources close to the company.

The TWC agreement will add 12 million households.

Epix was launched in October 2009 after Paramount and the two other studios failed to agree to a deal with CBS’ Showtime. Instead, they started their own venture.

Cable operators said then they wouldn’t carry the service, maintaining that the desire for premium channels was more than satisfied by current players.

Last year, however, all the premium channels increased subscriber numbers, as has Netflix, as consumers hoover up low-cost entertainment options.

It appears the TWC agreement won’t be impacted by Comcast’s $45 billion proposed acquisition of the service, a source close to the firm said.